Expandable catheter assembly with flexible printed circuit board (pcb) electrical pathways

ABSTRACT

Provided is a flex-PCB catheter device that is configured to be inserted into a body lumen. The flex-PCB catheter comprises an elongate shaft, an expandable assembly, a flexible printed circuit board (flex-PCB) substrate, a plurality of electronic components and a plurality of communication paths. The elongate shaft comprises a proximal end and a distal end. The expandable assembly is configured to transition from a radially compact state to a radially expanded state. The plurality of electronic elements are coupled to the flex-PCB substrate and are configured to receive and/or transmit an electric signal. The plurality of communication paths are positioned on and/or within the flex-PCB substrate. The communication paths selectively couple the plurality of electronic elements to a plurality of electrical contacts configured to electrically connect to an electronic module configured to process the electrical signal. The flex-PCB substrate can have multiple layers, including one or more metallic layers. Acoustic matching elements and conductive traces can be includes in the flex-PCB substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 16/242,810, filed Jan. 8, 2019, which is acontinuation application of U.S. patent application Ser. No. 14/762,944,filed Jul. 23, 2015, which is a 371 national stage application of PatentCooperation Treaty Application No. PCT/US2014/015261 filed Feb. 7, 2014,entitled EXPANDABLE CATHETER ASSEMBLY WITH FLEXIBLE PRINTED CIRCUITBOARD (PCB) ELECTRICAL PATHWAYS, which in turn claims priority under 35USC 119(e) from U.S. Provisional Patent Application 61/762,363, filedFeb. 8, 2013, entitled DEVICE AND METHOD FOR THE GEOMETRIC DETERMINATIONOF ELECTRICAL DIPOLE DENSITIES ON THE CARDIAC WALL, the disclosures ofwhich are incorporated herein by reference in their entireties.

The present application, while not claiming priority to, may be relatedto U.S. Patent Application Ser. No. 61/695,535, entitled SYSTEM ANDMETHOD FOR DIAGNOSING AND TREATING HEART TISSUE, filed Aug. 31, 2012,which is incorporated herein by reference by its entirety.

FIELD OF INTEREST

The invention relates to the field of medical devices used within thebody, and more particularly to the field of medical devices comprisingexpandable assemblies, e.g., such as expandable catheters used inelectrophysiology, and methods for using such devices and expandableassemblies.

BACKGROUND

The use of electrodes within a body for measuring certain electricalcharacteristics of the heart is routinely performed, sometimes referredto as cardiac mapping. And the use of ablation catheters to selectivelyablate nerves or tissue, for example, within the body is also routinelyperformed. Cardiac mapping and ablation are performed separately, usingdifferent, specialized devices or systems.

An ablation catheter can be used, for example, in a medical procedure totreat some types of arrhythmias, which are problems with the rate orrhythm of the heartbeat. An ablation catheter is a long, thin, flexibletube that is put into a blood vessel in the arm, groin (upper thigh), orneck of the patient and guided into the heart through the blood vessel.In catheter ablation, radiofrequency (RF) energy is usually used toproduce heat that selectively destroys the heart tissue.

For cardiac mapping, as an example, currently electrodes can belocalized within the body either by a permanent magnetic field, amagnetic field generated by electromagnets, or an impedance measurement.

The Carto 3 System by Biosense Webster, Inc. is an example of anelectromagnetic field measurement system, in accordance with the priorart. Such a system needs specialized electrodes with electromagneticcoils.

The Localisa® Intracardiac Navigation System by Medtronic, Inc. is anexample of an impedance measurement system, in accordance with the priorart. (Localisa is registered as a United States trademark by MedtronicInc.) Such a system can be inaccurate due to tissue anisotropy andrespiration.

SUMMARY

According to one aspect, a device that is configured to be inserted intoa body lumen comprises an elongate shaft comprising a proximal end and adistal end; an expandable assembly configured to transition from aradially compact state to a radially expanded state; a flexible printedcircuit board (flex-PCB) substrate; a plurality of electronic elementscoupled to the flex-PCB substrate and configured to at least one ofreceive or transmit an electrical signal; and a plurality ofcommunication paths positioned at least one of on or within the flex-PCBsubstrate and selectively coupling the plurality of electronic elementsto a plurality of electrical contacts configured to electrically connectto an electronic module configured to process the electrical signal.

The expandable assembly can be further configured for insertion into aheart chamber.

The device can comprise a dipole mapping device.

The device can be insertable in a body lumen selected from a groupcomprising: a femoral vein; a femoral artery; an intrajugular vein; anintrajugular artery; the Vena Cava; and combinations of these.

The electrical signal can comprise a signal selected from a groupcomprising: electrical power; an information signal; a sensor signal; acontrol signal; and combinations of these.

The electronic module is configured to perform a function selected agroup comprising: transmitting a power signal; transmitting a drivesignal; transmitting an information signal; receiving an informationsignal; receiving a sensor signal; processing an information signal;analyzing an information signal; and combinations of these.

At least some of the plurality of electronic elements can be fixedlyattached to the flex-PCB substrate and/or the expandable assembly.

At least one of the plurality of electronic elements can comprise atleast one element selected from a group comprising: an electrode; anultrasound transducer; an accelerometer; a sensor; a transducer; andcombinations of these.

At least one of the plurality of electronic elements can comprise asensor selected from a group comprising: a temperature sensor; apressure sensor; a strain gauge; and combinations of these.

At least one of the plurality of electronic elements can comprise atransducer selected from a group comprising: a sound transducer; anultrasound transducer; an electrode; a heating element; a coolingelement; and combinations of these.

The plurality of electronic elements can comprise at least two differenttypes of electronic elements. For example, the at least two types ofelectronic elements can comprise at least one electrode and at least oneultrasound transducer. The plurality of electronic elements can compriseat least four electrodes and at least four ultrasound transducers. Theplurality of electronic elements can comprise at least six electrodesand at least six ultrasound transducers. The plurality of electronicelements can comprise at least eight electrodes and at least eightultrasound transducers.

At least one of the plurality of electronic elements can comprise atleast one electrode. The at least one electrode can comprise anelectrode deposited on the flex-PCB substrate. The at least oneelectrode can comprise an electrode deposited using a deposition processselected from a group comprising: electro-deposition; ion beamdeposition; sputtering; and combinations of these. The at least oneelectrode can comprise a material selected from a group comprising:copper; gold; platinum; iridium; stainless steel; and combinations ofthese. The at least one electrode can comprise a conductive coating, forexample a conductive coating selected from a group comprising: iridiumoxide; Platinum Black; PEDOT; carbon nanotubes; and combinations ofthese.

At least one of the plurality of electronic elements can comprise anultrasound transducer. The flex-PCB substrate can comprise anelectrically conductive pad and the ultrasound transducer can beelectrically connected to the electrically conductive pad. The devicecan further comprise a housing configured to maintain the ultrasoundtransducer in electrical contact with the conductive pad. The device canfurther comprise a clip configured to secure the ultrasound transducerto the flex-PCB substrate. The ultrasound transducer can be soldered tothe conductive pad.

The plurality of electronic elements can comprise a plurality ofultrasound transducers. The expandable assembly can comprise at leasttwo splines with at least two ultrasound transducers mounted to eachspline. The at least two ultrasound transducers mounted to a firstspline can be linearly staggered from at least two ultrasoundtransducers mounted to a second spline, such that a protrusion of anultrasound transducer on the first spline extends between protrusions ofthe at least two ultrasound transducers on the second spline.

The plurality of electronic elements can be configured to transmitand/or receive signals from the electronic module via the plurality ofcommunication paths.

The plurality of electronic elements can comprise one or morepiezoelectric transducers (PZT). The one or more piezoelectrictransducers can comprise a matching layer, an active element on thematching layer, and a backing material on the active element. Thematching layer can be a quarter-wave matching layer based on immersionin blood. The matching layer can be part of a metallic layer of theflex-PCB substrate. The plurality of communication paths can compriseconductive traces formed within the flex-PCB substrate. The conductivetraces can be formed around pads of the matching layer. The conductivetraces can form part of a first metallic layer of the flex-PCB substrateand the matching layer can be a second metallic layer of the flex-PCBsubstrate.

The expandable assembly can comprise a spline support, and the flex-PCBsubstrate can be attached to the spline support in one or morelocations. For example, the flex-PCB substrate can be attached to thespline support in two or more discrete locations, where at least two ofthe two or more discrete locations are separated by a region in whichthe flex-PCB substrate and the spline support are unattached. The devicecan further comprise an adhesive, at least one crimp, and/or at leastone capture element that attaches the flex-PCB substrate to the splinesupport in the one or more locations.

The flex-PCB substrate can comprise materials selected from a groupcomprising: polyimide; polyester; nylon; Pebax; liquid crystal polymer;and combinations of these.

The flex-PCB substrate can have a laminate construction, for example alaminate construction comprising multiple layers of conductors.

The flex-PCB substrate can comprise a first layer with a first set ofconductors and a second, opposing layer with a second set of conductors.The flex-PCB substrate can further comprise at least one via between thefirst layer and the second layer.

The plurality of electronic elements can comprise at least oneelectronic element selected from a group comprising: a multiplexer; atransducer; a sensor; an A/D converter; a D/A converter; an electric tooptical signal converter; an optical to electrical signal converter; ananalog signal filter; a digital signal filter; an amplification circuit;a pre-amplification circuit; and combinations of these.

The flex-PCB can comprise a distal end where the expandable assembly ispositioned; a proximal end comprising the plurality of electricalcontacts; and a middle portion therebetween comprising at least portionsof the plurality of communication paths, where the middle portionsubstantially extends into the shaft. The flex-PCB substrate proximalend can be positioned proximal to the shaft proximal end.

The device can further comprise at least one communication conduit,where the at least one communication conduit can comprise a distal endelectrically attached to the flex-PCB substrate and an elongate portionthat extends through a majority of the length of the shaft. The at leastone communication conduit can comprise a conduit selected from a groupcomprising: a wire; a trace; a coaxial cable; an optical fiber; andcombinations of these. The at least one communication conduit cancomprise at least one micro coaxial cable.

The flex-PCB can comprise a plurality of splines, and each spline cancomprise a connection region comprising a series of electricalconnection points, where the connection regions are arranged linearlyabout a central axis of the expandable assembly, and where at least oneof the connection regions are staggered with respect to at least oneother connection region.

The device can further comprise a second flex-PCB substrate comprising asecond plurality of electronic elements coupled to the second flex-PCBsubstrate and configured to at least one of receive or transmit anelectrical signal and a second plurality of communication pathspositioned at least one of on or within the second flex-PCB substrateand selectively coupling the second plurality of electronic elements tothe plurality of electrical contacts configured to electrically connectto the electronic module. The expandable assembly can comprise at leasta first spline and a second spline, where the first flex-PCB substratecan be attached to the first spline and the second flex-PCB substratecan be attached to the second spline. The first flex-PCB substrate canhave a first length and a connection region at a proximal end of thefirst flex-PCB substrate, and the second flex-PCB substrate can have asecond length and a second connection region at a proximal end of thesecond flex-PCB substrate, and the first and second connection regionscan be arranged linearly about a central axis of the expandableassembly, where the second length can be longer than the first lengthand the first connection region can be positioned at a more proximallocation than a location of the second connection region.

The expandable assembly can comprise between two and eight flex-PCBsubstrates, where each flex-PCB substrate comprises multiple electronicelements from the plurality of electronic elements and multiplecommunication paths from the plurality of communication paths thatcouple the multiple electronic elements from each flex-PCB substrate tothe electronic module. For example, the expandable assembly can comprisetwo to eight splines and each of the flex-PCB substrates is attached toa different spline.

The plurality of communication paths can comprise one or more conductorscomprising a material from a group comprising: copper; gold; platinum;silver; and combinations of these.

The plurality of electronic elements can comprise multiple ultrasoundtransducers and wherein at least one of the plurality of communicationpaths is electrically connected to the multiple ultrasound transducers.The at least one communication path comprise at least one coaxial cablecomprising a shield and an inner conductor, and the multiple ultrasoundtransducers can be electrically connected to the coaxial cable shield.

The plurality of electronic elements can comprise at least one electrodeand at least one ultrasound transducer, and at least one of theplurality of communication paths can be electrically connected to the atleast one electrode and the at least one ultrasound transducer. The atleast one communication path can comprise at least one coaxial cablecomprising a shield and an inner conductor, and the at least oneelectrode and the at least one ultrasound transducer can be electricallyconnected to the coaxial cable inner conductor. The at least onecommunication path can comprise multiple coaxial cables each comprisinga shield and an inner conductor, wherein the multiple coaxial cableshields can be electrically connected. For example, the at least oneelectrode can comprise a first electrode and a second electrode, and afirst coaxial cable inner conductor can be electrically connected to thefirst electrode and a second coaxial cable inner conductor can beelectrically connected to the second electrode.

The plurality of electrical contacts can be configured to be removablyattached to the electronic module.

The plurality of electrical contacts can comprise an electricalconnector, for example at least one of a plug or a jack.

The elongate shaft can define an elongate lumen. The lumen can extendbetween the shaft proximal end and distal end. The lumen can beconfigured to slidingly receive a guide wire and/or a shaft of a seconddevice, for example an ablation catheter.

The shaft can comprise a steerable shaft.

The expandable assembly can be attached to the distal end of the shaft.

The shaft can comprise a distal portion, and the expandable assembly canbe positioned on the shaft distal portion.

The shaft can define a lumen, and the expandable assembly can beconfigured to be advanced from within the lumen of the shaft.

The expandable assembly can comprise an array of splines comprising atleast portions of the flex-PCB substrate. The plurality of electronicelements can be coupled to one or more splines in the array of splines.The flex-PCB substrate can have a substrate width and a first spline canhave a first spline width approximately the same as the first substratewidth. The flex-PCB substrate can be coupled to two or more splines fromthe array of splines.

The expandable assembly can comprise a plurality of splines forming abasket array or basket catheter, and the plurality of electronicelements can comprise a plurality of electrodes and a plurality ofultrasound transducers, where a plurality of electrodes and a pluralityof ultrasound transducers are provided on each spline. Each spline cancomprise a plurality of pairs of electrodes and ultrasound transducers,with one electrode and one ultrasound transducer per pair. The flex-PCBsubstrate can comprise at least one metallic layer comprising at leastsome of the plurality of communication paths in the form of conductivetraces selectively connecting the plurality of electrodes and pluralityof ultrasound transducers to connection points at proximal ends of thesplines. The plurality of ultrasound transducers on each spline canshare a single conductive trace. One or more wires or cables can connectthe connection points to the plurality of electrical contacts.

The expandable assembly can be biased in an expanded state.

The expandable assembly can be biased in a contracted state.

The device can further comprise a handle attached to the proximal end ofthe shaft.

The device can further comprise a sheath with a proximal end, a distalend and a lumen therebetween, where the lumen can be constructed andarranged to slidingly receive the elongate shaft and the expandableassembly. The expandable assembly can be configured to radially expandas it exits the sheath lumen.

According to another aspect, a flex-PCB catheter configured to beinserted into a body lumen comprises an expandable assembly configuredto transition from a radially compact state to a radially expandedstate; a flexible printed circuit board (flex-PCB) substrate; aplurality of electronic elements coupled to the flex-PCB substrate andconfigured to at least one of receive or transmit an electrical signal;and a plurality of communication paths positioned at least one of on orwithin the flex-PCB substrate and selectively coupling the plurality ofelectronic elements to a plurality of electrical contacts configured toelectrically connect to an electronic module configured to process theelectrical signal.

According to another aspect, a method of interacting with a body via abody lumen comprises providing a device having: an elongate shaftcomprising a proximal end and a distal end, an expandable assemblyconfigured to transition from a radially compact state to a radiallyexpanded state, a flexible printed circuit board (flex-PCB) substrate, aplurality of electronic elements coupled to the flex-PCB substrate andconfigured to at least one of receive or transmit an electrical signal,and a plurality of communication paths positioned at least one of on orwithin the flex-PCB substrate and selectively coupling the plurality ofelectronic elements to a plurality of electrical contacts configured toelectrically connect to an electronic module configured to process theelectrical signal; introducing the expandable assembly into a region ofthe body and expanding the expandable assembly; and supplying at leastone electrical signal to the plurality of electronic elements via atleast some of the plurality of communication paths. The region of thebody can comprise a cardiac chamber.

In various embodiments of the method, the device can be configured andarranged in accordance with one or more of the embodiments describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent in view of the attacheddrawings and accompanying detailed description. The embodiments depictedtherein are provided by way of example, not by way of limitation,wherein like reference numerals refer to the same or similar elements.The drawings are not necessarily to scale, emphasis instead being placedupon illustrating aspects of the invention. In the drawings:

FIG. 1 is a side view of an embodiment of a catheter system comprising aflexible printed circuit board (“flex-PCB”) catheter, in accordance withaspects of the inventive concepts;

FIGS. 2A and 2B provide bottom and top views of portions of anembodiment of a flexible printed circuit board (“flex PCB”) that cancomprise an expandable assembly, in accordance with aspects of theinventive concepts;

FIGS. 3A and 3B provide schematic diagrams showing an embodiment of anelectrical layout of the flex-PCB catheter and related apparatuses ofFIGS. 2A and 2B, in accordance with aspects of the inventive concepts;

FIG. 4 is a perspective view of an embodiment of proximal ends offlex-PCB splines having staggered connection portions, in accordancewith aspects of the inventive concepts;

FIG. 5 is a perspective view of an embodiment of a portion of anexpandable assembly in a collapsed state, in accordance with aspects ofthe inventive concepts;

FIG. 6 is a perspective view of an embodiment of a flex-PCB layer of aflex-PCB expandable assembly, in accordance with aspects of theinventive concepts;

FIGS. 7A and 7B are perspective views of an embodiment of a flex-PCBcatheter and portions thereof, in accordance with aspects of theinventive concepts;

FIG. 7C shows an exploded view of an embodiment of a multi-layer spline,in accordance with aspects of the inventive concepts;

FIG. 8 shows a portion of another embodiment of a spline of a flex-PCBcatheter, in accordance with aspects of the inventive concepts;

FIG. 9A is a perspective view of an embodiment of a flex-PCB catheter,in accordance with aspects of the inventive concepts;

FIG. 9B is a front view of an embodiment of the flex-PCB catheter ofFIG. 9A in a collapsed state within an outer shaft, in accordance withaspects of the inventive concepts; and

FIG. 10 is a perspective view of another embodiment of a flex-PCBcatheter, in accordance with aspects of the inventive concepts.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Various exemplary embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exemplaryembodiments are shown. The present inventive concept can, however, beembodied in many different forms and should not be construed as limitedto the exemplary embodiments set forth herein.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are used to distinguish oneelement from another, but not to imply a required sequence of elements.For example, a first element can be termed a second element, and,similarly, a second element can be termed a first element, withoutdeparting from the scope of the present invention. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that when an element is referred to as being “on”or “connected” or “coupled” to another element, it can be directly on orconnected or coupled to the other element or intervening elements can bepresent. In contrast, when an element is referred to as being “directlyon” or “directly connected” or “directly coupled” to another element,there are no intervening elements present. Other words used to describethe relationship between elements should be interpreted in a likefashion (e.g., “between” versus “directly between,” “adjacent” versus“directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including,” when used herein, specifythe presence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like may be used to describe an element and/or feature'srelationship to another element(s) and/or feature(s) as, for example,illustrated in the figures. It will be understood that the spatiallyrelative terms are intended to encompass different orientations of thedevice in use and/or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” and/or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.The device can be otherwise oriented (e.g., rotated 90 degrees or atother orientations) and the spatially relative descriptors used hereininterpreted accordingly.

FIG. 1 is a side view of an embodiment of a catheter system comprising aflexible printed circuit board (“flex-PCB”) catheter, in accordance withaspects of the inventive concepts.

In the embodiment of FIG. 1 , a catheter system 2 includes an introducer10 and a flex-PCB catheter 100. In this embodiment, the introducer 10includes a handle 12 and a shaft 14 that includes at least one lumen. Insome embodiments, introducer 10 comprises a standard transseptal accesssheath or other device configured to provide access to a body space suchas a heart chamber. The shaft 14 is configured to slidingly receiveand/or accommodate translation of the flex-PCB catheter 100 within theshaft 14. Handle 12 can include a knob, lever, switch or other control,such as control 13 that is configured to steer and/or deflect the distalend of introducer 10 and/or perform another function. In the exampleembodiment of FIG. 1 , the handle 12, control 13, and shaft 14 aregenerally known in the art, so not discussed in detail herein.

The flex-PCB catheter 100 includes a handle 112 and an elongate,flexible shaft 114, extending from handle 112. Attached to the distalend of shaft 114 is a radially expandable and/or compactable assembly,expandable assembly 110. In an alternative embodiment, expandableassembly 110 is mounted to a distal portion of shaft 114, proximal tothe distal end of shaft 114. In some embodiments, expandable assembly110 is attached to shaft 114 as described in reference to applicant'sco-pending U.S. Patent Application Ser. No. 61/695,535, entitled SYSTEMAND METHOD FOR DIAGNOSING AND TREATING HEART TISSUE, filed Aug. 31,2012, which is incorporated herein by reference by its entirety. Shaft114 and expandable assembly 110 are constructed and arranged to beinserted into a body (e.g., a human body) through a body vessel, such asa blood vessel. Such blood vessel can include a femoral vein, femoralartery, intrajugular vein, intrajugular artery, and vena cava, asexamples. The expandable assembly 110 can, for example, be or include adipole mapping device, e.g., for mapping electrical activity of theheart. In some embodiments, handle 112 includes a knob, lever, switch orother control, control 113. Control 113 can be configured to perform afunction such as, for example, steering the distal end of shaft 114;controlling the expansion and/or contraction of expandable assembly 110such as via retraction or advancement, respectively, of one or morecontrol rods not shown, making an electrical connection such as toprovide power to a component of expandable assembly 110 or electricallyconnecting to a sensor of expandable assembly 110, and combinations ofthese.

A set of one or more electrical, optical, or electro-optical wires orcables (e.g., coaxial wire or cable) 115 (collectively, “wires 115”) canbe provided as a communication path between the flex-PCB catheter 100 anexternal electrical component or system, such as electronic module 360.The wires 115 can extend through the shaft 114 to an opening in thehandle 112, and terminate at one or more electrical connections (ECs)116. The electrical connections 116 can take the form of plugs, jacks,or other connectors configured for removable attachment or coupling toelectronic module 360 and/or another computer or otherwiseelectrically-based system, such as through electrical signal conduits361, as shown. Such external systems can include, as examples, a powerdelivery system, an electrical recording system, an ultrasonic imagingor driving system, a display system, a diagnostic system, a medicaltreatment system, or combinations thereof, which can be userinteractive.

In various embodiments, the expandable assembly 110 can be resilientlybiased in a radially expanded state (e.g. a resiliently biased array ofnickel titanium alloy filaments). For example, the expandable assembly110 can be resiliently biased in a radially expanded state such that itcan be radially compacted and positioned within shaft 14 and self-expandwhen the confinement within shaft 14 is relieved, such as when the shaft14 is retracted relative to shaft 114 and/or when shaft 114 is advancedrelative to shaft 14 such as to cause expandable assembly 110 to exitthe distal end of shaft 14. In other embodiments, the expandableassembly 110 can be resiliently biased in a collapsed or radiallycompacted state, such as when a control rod or other mechanism is usedto radially expand the expandable assembly 110.

The flex-PCB catheter 100, in this embodiment, includes a set of splines120 that include at least one flex-PCB layer, which can be referred toas flex-PCB splines. The flex-PCB layer can be attached to a flexiblefilament, such as a metal (e.g. nickel titanium alloy) or plasticfilament. In this embodiment, a plurality of the splines 120 have aflex-PCB configuration that includes at least one flex-PCB substrate orbase layer, substrate 200 on or within which a plurality of activeand/or passive electrical, optical, or electro-optical elements (EEs)150, collectively referred to as “electronic elements 150” are providedwith accompanying communication paths 102, e.g., electrical, optical, orelectro-optical communication paths.

Electronic elements 150 can be configured to receive and/or transmit anelectrical signal, such as an electrical signal selected from a groupcomprising: electrical power, an information signal, a sensor signal, acontrol signal, and combinations thereof. These electrical signals canbe transmitted from, received by, and/or otherwise processed byelectronic module 360 or other external device as described hereinabove. In some embodiments, electronic module 360 processing comprises afunction selected from a group comprising: transmitting a power signal,transmitting a drive signal, transmitting an information signal,receiving an information signal, receiving a sensor signal, processingan information signal, analyzing an information signal, and combinationsthereof.

The flex-PCB catheter 100 can include connection points 104, wherein thecommunication paths 102 couple the electronic elements 150 to theconnection points 104 according to a specified circuit layout. In thisembodiment, the wires 115 couple the connection points 104 to theexternal electrical connections (ECs) 116 via or within shaft 114 forconnection or communication with electronic module 360. As shown in FIG.1 , connection points 104 are typically positioned within a distalportion of shaft 114.

In some embodiments, wires 115 each include a conductor surrounded by aninsulator, such as a coaxial cable, which can include a shieldsurrounding the conductor in addition to the insulator. In someembodiments, wires 115 comprise conductive traces positioned on aflexible printed circuit board (flex-PCB) substrate, such as whensubstrate 200 further comprises wires 115 (e.g. when substrate 200extends proximally through shaft 114, such as to couple electronicelements 150 to the external electrical connections 116, avoiding theneed for connection points 104).

In various embodiments, the flex-PCB catheter 100 can be considered toinclude the expandable assembly 110, comprising the electronic elements150, formed at a distal end and the connection points 104 formed at aproximal end (near or within shaft 114). The expandable assembly 110can, in some embodiments, take to the form of an array, such as a basketarray, as in FIG. 1 . In such cases, the expandable assembly 110 can bereferred to as a flex-PCB basket catheter. The basket array can beconfigured to have the above-mentioned biasing in an expanded orcollapsed state, such as an array of nickel-titanium or other flexiblesplines one or more of which includes a flex-PCB attached thereto.Flex-PCB substrate 200 can be attached to expandable assembly 110 withan attachment element 201, such as an adhesive, a clip, a crimp, atattachment element or the like. In some embodiments, flex-PCB substrate200 is continually attached along a length of one or more splines 120.Alternatively or additionally, flex-PCB substrate 200 can be attachedalong a length of one or more splines 120 with one or more attachmentelements 201 positioned at one or more discrete attachment locations (asshown in FIG. 1 ), such as to allow independent flexing of flex-PCBsubstrate 200 and splines 120 alongside or in-between the one or moreattachment elements 201 (e.g. bending at an unattached segment allowsrelative movement between flex-PCB substrate and spline 120 at thatsegment, decreasing the rigidity of expandable assembly 110 whenflex-PCB substrate 200 is attached).

In various embodiments, the splines 120 can have the same length ordifferent lengths. And in some embodiments, the connection points 104 ondifferent splines 120 can be staggered to accommodate a tight collapsedor contracted configuration of the expandable assembly 110, as will bediscussed below.

In various embodiments, the electronic elements 150 can include morethan one type of electrical, optical, or electro-optical components.Therefore, different types of electrical components can be included onor in one or more splines 120 to accommodate one or more active and/orpassive functions. In some embodiments, different splines 120 caninclude different numbers, types, and/or arrangements of electronicelements 150.

As examples, types of electronic elements 150 can include, but are notlimited to, electrodes, transducers, accelerometers, sensors, integratedcircuits (e.g., semiconductors), and so on. As examples, such sensorscan include, but are not limited to, temperature sensors, pressuresensors (e.g., strain gauges), voltage sensors, current sensors,acoustic sensors, and so on. As examples, such transducers can include,but are not limited to, ultrasound transducers, sound transducers,heating elements, cooling elements, and so on. The integrated circuitscould include, but are not limited to, multiplexers (MUX),demultiplexers (DEMUX), A/D converters, D/A converters,electrical/optical converters, optical/electrical converters, analog ordigital signal filters (or other filters), amplifiers, pre-amplifiers,transducers, combinations thereof, and so on. For instance, a MUX can beused to reduce the number of wires to the expandable assembly 110. AnA/D converter could be used to reduce wires and/or reduce or eliminatenoise susceptibility such as to avoid a need for coax cables. Anamplifier can be used to boost one or more signals.

FIGS. 2A and 2B provide bottom and top views, respectively, of portionsof an embodiment of a flex-PCB substrate 200 that forms part of thespline 120 of the expandable assembly 110 of FIG. 1 , in accordance withaspects of the inventive concepts. For the purposes of this description,the bottom view is a perspective from within the expandable assembly 110and the top view is a perspective from outside the expandable assembly110. Each of the splines 120 includes a span or length 214 between theelectrode regions 212 and connection portion 216.

In various embodiments, the flex-PCB substrate 200 can include a singlelayer or a multilayer flex-PCB, each of which can comprise electricalpathways on one or both sides (i.e.

single sided or double sided). In the embodiment of FIGS. 2A and 2B, theflex-PCB substrate 200 has a multi-layer construction, where the layersare laminated together, with the flex-PCB substrate comprising theconnection points 104 and communication paths 102, and supporting theelectronic elements 150. The communication paths 102 and connectionpoints 104 can be formed on either or both sides of, or within, theflex-PCB substrate 200, or combinations thereof. Similarly, theelectronic elements 150 can be mounted on either or both sides of, ordisposed within, the flex-PCB substrate 200, or combinations thereof.

In this embodiment, the electronic elements 150 are arranged at thedistal end of the flex-PCB substrate 200 in an electrode region 212 andthe connection points 104 are arranged at the proximal end of theflex-PCB substrate 200 in a connection portion 216, with thecommunication paths 102 coupling specific connection points 104 withspecific electronic elements 150 across a span or length 214 of theflex-PCB substrate 200.

FIG. 2A shows a bottom view of the flex-PCB substrate 200. Part (A)shows a substantially complete bottom view of the flex-PCB substrate200. Part (B) shows a view of the electrode region 212 of the flex-PCBsubstrate 200, comprising portions of a bottom cover layer 210 andportions of a metallic layer 220 forming part of the expandable assembly110. Part (C) shows a view of the metallic layer 220 from Part (B) inthe electrode region 212. Part (D) shows a view of a portion of themetallic layer 220 from Part (C). Part (E) shows a view of theconnection portion 216 of the flex-PCB substrate 200, comprisingportions of the bottom cover layer 210 and portions of the metalliclayer 220 forming part of the connection points 104 in the connectionportion 216. And part (F) shows a view of the metallic layer 220 fromPart (E).

In the bottom view of FIG. 2A, the flex-PCB substrate includes thebottom cover layer 210 and the metal or metallic layer 220 that isdisposed on the bottom cover layer 210. In the embodiment of FIGS. 2Aand 2B, the communication paths 102 take the form of one or moreconductive traces of the metallic layer 220 formed on or within theflex-PCB substrate 200.

In the connection portion 216 of the flex-PCB substrate 200, themetallic layer 220 includes metallic pads 222 provided in the form ofvias (pathways which provide an electrical connection from one side of alayer to the opposite side), which comprise the connection points 104.That is, openings are formed in the bottom cover layer 210 to expose thepads 222, as the connection points 104.

In the electrode region 212 of the of the metallic layer 220, having theexpandable assembly 110, metallic pads 224 are provided as bases for atleast some of a first set of the electronic elements 150. For example,in this embodiment, the metallic pads 224 can be piezoelectrictransducer (PZT) pads used to support one or more ultrasound elements(not shown). Openings are formed in the bottom cover layer 210 to exposethe metallic pads 224. Between the metallic pads 224, also as part ofthe metallic layer 220, a second set of electronic elements 150 can beprovided, e.g., in the form of electrodes 152. In this embodiment, theelectrodes 152 are provided between metallic pads 224, and ultimatelybetween individual ones of the first set of electronic elements (e.g.,ultrasound crystals) mounted on the metallic pads 224.

FIG. 2B shows a top view of the flex-PCB substrate 200. Part (A) shows asubstantially complete top view of the flex-PCB substrate 200. Part (B)shows a view of the electrode region 212 of the flex-PCB substrate 200,comprising portions of a top cover layer 230 and portions of themetallic layer 220 forming part of the expandable assembly 110. Part (C)shows a view of the metallic layer 220 from Part (B). Part (D) shows aview of a portion of the metallic layer 220 from Part (C). Part (E)shows a view of the connection portion 216 of the flex-PCB substrate200, comprising portions of the top cover layer 230 and portions of themetallic layer 220 forming part of the connection points 104. And part(F) shows a view of the metallic layer 220 from Part (E).

In the embodiment of FIG. 2B, there is shown the top cover layer 230 andthe metallic layer 220. The top cover layer 230 is combined with thebottom cover layer 210, with the metallic layer 220 maintained betweenthe bottom and top cover layers 210 and 230 respectively. In thisembodiment, the top cover layer 230 substantially covers thecommunication paths 102 of the flex-PCB substrate 200. The top coverlayer 230 also covers the metallic pads 224 which are constructed andarranged to provide acoustic matching in the expandable assembly 110portion of the spline 120. Ultrasound crystals, as an example, can laterbe mounted on the top cover layer 230 and the metallic pads 224, as willbe discussed below. The electrodes 152 can also be mounted on the topcover layer 230 and connect to the metallic layer 220 through the topcover layer 230.

In the connection portion 216 of the flex-PCB spline 120 openings areformed in the top cover layer 230 to expose the pads 222, as theconnection points 104.

In the metallic layer 220, traces and pads can be made of electricallyconductive materials that can be formed by laser cutting, chemicaletching, molding or casting, and/or by printing, as examples. The bottomcover layer 210 can be laser cut and laminated to the metallic layer 220or the metallic layer 220 can be deposited and etched directly to thebottom cover layer 210, in various embodiments. The top cover layer 230can be laminated onto the bottom cover layer 210, with the metalliclayer 220 in between.

In the embodiment of FIGS. 2A and 2B, the flex-PCB substrate 200supports eight (8) sets of electronic elements 150 (e.g. 16 components)for a given spline 120. In other embodiments, a different number of setsof electronic elements 150 could be used, e.g., 2, 4, or 6 sets ofelectronic elements per spline 120. In the present example embodiment,each set of electronic elements 150 includes one electrode 152 and onecorresponding ultrasound transducer coupled to one correspondingmetallic pad 224. The electrodes 152 can comprise one or more coatings,such as a coating constructed and arranged to reduce impedance at one ormore ranges of frequencies, as an example. The ultrasound transducers,as an example, can be mounted to the flex-PCB substrate 200 in any of avariety of ways, e.g., they can be contained within cups or a housing,in some embodiments. (See, e.g., FIG. 8 .)

In various embodiments, the metallic pads 224 of the metallic layer 220can serve as an acoustic matching layer that maximizes the powertransfer and efficiency of a corresponding transducer (e.g., anultrasound transducer). The metallic pads 224 are specificallyconfigured to match the acoustic impedance of the transducer material(e.g., PZT) to that of the propagating medium (water, blood, etc.).

Optimal impedance matching is achieved when the matching layer thicknessis a quarter (¼) wavelength at an operating frequency within thatmaterial when the acoustic impedance is given byZ_match=sqrt(Z_transducer *Z_media). It can be difficult to find orengineer a material to have the exact acoustic impedance for aquarter-wave matching layer, thus, the thickness and acoustic impedancecan be varied in order to minimize losses. Composite or multi-layermaterials can be used for matching layers, in various embodiments. Theloss due to impedance mismatch of the matching layer can be calculatedor simulated, and the particulars of the metallic pads 224 determinedtherefrom.

In the present embodiment, the flex-PCB substrate 200 can be configuredas, or to include, a matching layer—as part of metallic layer 220. Forexample, a polyimide layer of the flex-PCB substrate can be configuredwith an acoustic impedance that can be used as a matching layer when thethicknesses of the bonding adhesive, metallized electrode, and substratelayers are controlled. The thickness of each of these layers in theflex-PCB substrate 200 design is selected to balance the tradeoffs ofacoustic and electrical performance, as well as the availability and/orcost of materials.

The bottom cover layer (or backing layer) 210 also affects the powertransfer efficiency and bandwidth of the transducer mounted on theflex-PCB substrate 200. The bottom cover layer 210 is selected tominimize the energy transmitted out of the back of the transducer, whilealso attenuating any acoustic energy that does enter the bottom coverlayer 210 (e.g. to increase the transducer bandwidth).

The electrodes 152 can be deposited directly on the bottom cover layer210, e.g. via electro-deposition, ion beam deposition, sputtering, andcombinations thereof. As an alternative to the deposition on the bottomcover layer 210, the electrodes 152 can be mounted to the flex-PCBsubstrate 200 (e.g. with an adhesive such as an insulating glue), thenelectrically connected to communication paths 102 within the flex-PCBsubstrate 200. In various embodiments, the electrodes 152 can be formedfrom copper, gold, platinum, iridium, stainless steel and/or otherconductive materials or elements. The electrodes 152 can optionally becoated with a surface coating, such as iridium oxide, platinum black (Ptblack), PEDOT (i.e., poly(3,4-ethylenedioxythiophene)), or carbonnanotubes, as examples.

In various embodiments, the communication paths 102 can be traces withinor on the flex-PCB substrate formed of copper, gold, platinum, orsilver, as examples. In various embodiments, the matching layer metallicpads 224 can be formed of copper, gold, platinum, or silver, asexamples. And in various embodiments, the bottom and top cover layers,210 and 230 respectively, can be formed of polyimide, polyester, nylon,polyether block amide (PEBA or PEBAX), liquid crystal polymer (LCP), andso on.

FIGS. 3A and 3B provide schematic diagrams showing an embodiment of anelectrical layout 300 of the flex-PCB catheter 100 of FIGS. 1, 2A and 2Bconnected to a set of corresponding coaxial cables 310 (as an example ofwires 115), in accordance with aspects of the inventive concepts. FIG.3A represents a schematic of an embodiment of connections of the coaxialcables 310 to the flex-PCB catheter 100. FIG. 3B represents a schematicof an embodiment of connections of the coaxial cables 310 to at leastone external system, electronic module 360, via the electricalconnections 116.

The electrical layout 300 shows the coaxial cables 310 comprising eight(8) coax cables, including coax cable 312, coupled to respective eight(8) electrodes 320, including electrode 322, which can be equivalent tothe electrodes 152, and to eight (8) ultrasound transducers 340,including ultrasound transducer 342. These elements, along with thecommunication paths 102 (e.g., conductive traces), are shown inschematic form in FIG. 3A.

Coax cable 312, as an example, includes an inner conductor 312 a, aninsulator 312 b, a shield 312 c, and a casing 312 d. The inner conductor312 a of coax cable 312 couples to the electrode 322 and then to aterminal of the ultrasound transducer 342. A second terminal of theultrasound transducer 342 couples to the shield 312 c of coax cable 312.In this embodiment, the second terminals of the ultrasound transducers340 can share a common wire or trace, as a manner of being commonlyconnected. The shields of all of the coax cables 310 are also commonlyconnected. In other embodiments, the second terminals of the ultrasoundtransducers 340 and/or shields need not be commonly connected, ordifferent sets of the second terminals of the ultrasound transducers 340and/or the shields can be commonly connected. In some embodiments, coaxcables 310 comprise an electrical characteristic selected from a groupcomprising: an approximate capacitance of 115 pF/meter at 1 kHz; acharacteristic impedance between 75 Ω and 1000 Ω; a characteristicimpedance of approximately 200 Ω; an attenuation of between 0.3 dB/meterand 1.0 dB/meter at 10 MHz; an attenuation of approximately 0.5 dB/meterat 10 MHz; and combinations of these.

The other coax cables 310 can have the same configuration andarrangement with their respective electrodes 320 and ultrasoundtransducers 340.

In the embodiment of FIG. 3B, the coax cables 310 are coupled toelectronic module 360. In this embodiment, the electronic module 360includes a patient isolation circuit 362, an electrode transceivercircuit 364, ultrasound transceiver circuit 366, a controller 368, and auser interface 370. The foregoing circuits can, as an example, form orbe part of an external system that provides cardiac activity analysis,mapping (e.g. recording and/or analysis of recorded electrical signals),treatment (e.g. providing ablative energy), or some combination thereof.

In the embodiment shown in the high-level schematic of FIG. 3B, theelectrode circuitry, ultrasound circuitry, user interface, andcontroller are electrically isolated from the patient (e.g. to preventundesired delivery of a shock or other undesired electrical energy tothe patient), via the patient isolation circuit 362, which can form partof electronic module 360 or can be separate therefrom.

FIG. 4 is a perspective view of an embodiment of the connection portions216 (i.e., proximal ends) of the splines 120 of an expandable assembly110, in accordance with aspects of the inventive concepts. In thisembodiment, the splines 120 have linearly staggered connection portions216 a, 216 b and 216 c (generally 216), and each connection portion 216has a set of linear staggered connection points 104 a, 104 b and 104 c(generally 104), respectively. Generally, the connection portions 216are on a portion of the flex-PCB catheter 100 that is contained within adistal portion of a shaft, such as shaft 114 of FIG. 1 . Linearstaggering of connection portions 216, and/or the linear staggering ofconnections points 104 allows an efficiently radially compact design ofa surrounding shaft, and/or a shaft through which the connectionportions 216 will be advanced through (e.g. shaft 14 of FIG. 1 ). Inthis embodiment, the proximal ends connection portions 216 a, 216 b, and216 c are staggered with respect to their locations on their respectivesplines 120 a, 120 b, and 120 c. Thus, the corresponding connectionportions 216 a, 216 b, and 216 c (and connection points 104 a, 104 b,and 104 c) of at least two splines 120 a, 120 b, and/or 120 c, are notdirectly adjacent and side-by-side to each other—they are offset orstaggered. This can be the case for some or all of the splines 120forming the flex-PCB catheter 100.

In FIG. 4 , the splines 120 are shown having different lengths, but inother embodiments the splines could be substantially the same length,with their connection portions at different locations on the splines.Thus, the connection portions would remain offset or staggered, even ifthe splines 120 are substantially the same length, and allow efficientradially compacting of splines 120 due to the staggered positioning.

FIG. 4 further includes a callout (A) that shows an embodiment of anarrangement of connections 104 b in the connection portion 216 b forspline 120 b. In this embodiment, nine connections are shown for spline120 b, in a linearly staggered arrangement as described above. Eight (8)connections are provided to eight (8) conductors via the flex-PCBsubstrate 200, such as the inner conductor 312 a of coax cable 312 inFIGS. 3A and 3B. A ninth connection is also provided to a shield as awire or trace shared by the eight (8) transducers on spline 120 b, e.g.,see transducers 340 and shield 312 c of coax cable 312 in FIGS. 3A). Inthis embodiment, the right-most connection is connected to the shield,but in other embodiments this need not be the case. This arrangement ofconnections can also be provided for one or more other splines in theexpandable assembly 110.

In this embodiment, the conductors (or wires) can be laser welded,bonded with conductive adhesive, or soldered to respective vias (see,e.g., pads 222 in FIGS. 2A and 2B). Each connection can have a verticaldimension (i.e., depth and/or height). Staggering connection portionsalleviates congestion caused by the vertical dimensions of theconnections, and the connection portions 216 generally, allowing anefficient, radially compact configuration of the portions of the deviceincluding the connection points 104.

FIG. 5 is a perspective view of an embodiment of a portion of anexpandable assembly 110 in a collapsed state, in accordance with aspectsof the present invention. In FIG. 5 , a backing layer is externallyvisible, such as the top cover layer 230 shown in FIG. 2B.

In this embodiment, the expandable assembly 110 includes six (6) splines120, including splines 120 a, 120 b, and 120 c. Each of the splines 120includes a plurality of first electronic element locations 520 and aplurality of second electronic element locations 530. Thus, two or moretypes of electronic elements 150 can be included in each spline 120. Asexamples, the first electronic element locations 520 can include oraccommodate ultrasound transducers, e.g. transducer 524, and the secondelectronic element locations 530 can include or accommodate electrodes,e.g., electrode 522.

In this embodiment, the first electronic element locations 520 are widerthan adjacent and/or intermediate regions of the splines 120, and thesecond electronic element locations 530, and are generally circular. Inother embodiments, the first electronic element locations 520 could havedifferent shapes. To facilitate a more compact arrangement of theexpandable assembly 110 and the splines 120, the first electronicelement locations 520 are staggered or offset from spline to spline.Therefore, a protrusion of one first electronic element location 520 onspline 120 a can be located between two protrusions of neighboring firstelectronic element locations 520 on neighboring spline 120 b, as anexample. This staggered arrangement can be provided for all of thesplines 120.

The embodiment of FIG. 5 shows substantially straight splines 120 withlaterally protruding first electronic element locations 520. In otherembodiments, the splines 120 need not be substantially straight. Forexample, the splines 120 could have plural curved sections (e.g., asinusoidal wave shape), a saw tooth or zigzag shape, a square waveshape, or some other shape that could create a staggered or interleavedarrangement of the expanded assembly 110 in the collapsed state. In suchcases, the first electronic element locations 520 need not have lateralprotrusions on one or both sides of the splines.

FIG. 6 is a perspective view of an embodiment of a flex-PCB substrate200 of the flex-PCB catheter 100 (e.g., a basket catheter), inaccordance with aspects of the inventive concepts. In this embodiment,the flex-PCB substrate 200 is configured to accommodate six splines 120.Each spline 120 defines a plurality of openings 602 in the electroderegions 212 to accommodate mounting of a plurality of electronicelements, such as ultrasound crystals as an example or other electronicelements 150 described in FIG. 1 .

The flex-PCB substrate 200 defines a central opening 604. The opening604 could accommodate passage of a guidewire and/or a second catheter,e.g., an ablation catheter, in some embodiments, described further inFIG. 10 .

The flex-PCB substrate 200 can be a single or multi-layer flex-PCB layermade as a single work piece. For example, the flex-PCB substrate 200could be laser cut from a single piece of flex-PCB material. As such,manufacturing complexity and time, and cost can be reduced.

Also, in this embodiment, the splines 120 have various lengths so thatthe connection portions can be staggered, as discussed above. But thisneed not be the case in all embodiments. In some embodiment, the splines120 can be substantially the same length.

FIGS. 7A-7B are perspective views of embodiments of a flex-PCB catheterand portions thereof, in accordance with aspects of the inventiveconcepts. The flex-PCB catheter can take the form of the flex-PCBcatheter 100 of FIGS. 1, 2A and 2B, as an example.

In the embodiment of FIG. 7A, the flex-PCB catheter 100 includes theexpandable assembly 110 (e.g., basket catheter) comprising six splines120. Each spline includes eight sets 730 of electronic elements 150,each set 730 comprising an ultrasound transducer 154 and an electrode152. In other embodiments, more or less splines could be provided, withdifferent numbers of electronic elements 150 and/or electronic elementsets 730.

Each of the splines 120 includes a span or length 214 between theelectrode regions 212 and connection portion 216, as described withrespect to FIGS. 2A, 2B and 4 . In an embodiment, the spans 214 andconnection portions 216 are maintained within a shaft (e.g. shaft 114 ofFIG. 1 ), in both the expanded state (as shown) and the collapsed stateof the expandable assembly 110. Also, in this embodiment, the splines120 have various lengths so that the connection portions 216 arelinearly staggered, minimizing the required diameter of shaft 114, asdiscussed above in relation to FIG. 4 .

Referring to FIG. 7B, in this embodiment, the ultrasound transducer 154is of the immersion type, since it can be immersed in blood within theheart, in the example embodiment. The ultrasound transducer 154comprises an acoustic matching layer 734, an active element (e.g., a PZTpad or electrode) 736, and a backing material (or cover) 738.

The flex-PCB catheter 100 of FIG. 7B includes the flex-PCB substrate 200having defined openings that are occupied by acoustic matching (orbalancing) pads 732. As an example, the acoustic matching pad 732 can besoldered or glued into place. The active element 736 can be mounted onthe acoustic matching pad 732, and the backing material 738 can bedisposed on the active element 736, as is shown.

In FIGS. 7A and 7B a spline support 750 is shown that can assist ingiving shape and/or shape biasing to the expandable assembly 110.

FIG. 7C shows an exploded view of embodiment of a multi-layer spline, inaccordance with aspects of the inventive concepts. The spline of FIG. 7Ccan be an embodiment of spline 120.

The portion of spline 120 in FIG. 7C comprises a first laminate layer762 (e.g., top cover layer 230 of FIG. 2B), a first metallic layer 764,a second laminate layer 766, a second metallic layer 768, a thirdlaminate layer 770 (e.g., bottom cover layer 210 of FIG. 2A), activeelements (e.g., PZT) 736, and backing material 738. The layers 762, 764,766, 768, and 770 can be laminated together to form an embodiment of theflex-PCB substrate 200.

In this embodiment, the first metallic layer 764 includes electrodes152, forming part of electronic element sets 730, balance traces 782disposed beneath the active elements 736, and an electrode trace 784that connects the electrodes 152. In the embodiment of FIG. 7C, eachactive element 736 has the same amount of balance pad (or trace) 782“underneath” it, which is different from the embodiment of FIGS. 2A and2B, where traces do not travel “beneath,” but around the metallic (e.g.,PZT) pads 224. In this configuration, balance traces 782 are positionedbeneath each element 736 and are configured to acoustically balance eachelement 736. In some embodiments, balance traces 782 do not carry anelectrical signal (i.e. traces 782 are not electrically connected to anyother electronic component or conductive trace). For example, along aspline 120, the area beneath each active element 736 can include a setof electrical traces including one or more electrode traces 784 and zeroor more balance traces 782. To achieve an acoustic or other mechanicalbalance, the total number of traces is the same quantity beneath eachactive element 736. For example, in a spline containing eight activeelements 736, the most proximal active element 736 will have eightelectrode traces 784 and zero balance traces 782 positioned beneath it,each successive more distal active element 736 will have one lesselectrode trace 784 and one more balance trace 782 positioned beneath it(as compared to the active element 736 just proximal to that activeelement 736), incrementally continuing to the most distal active element736 which has one electrode trace 784 and seven balance traces 782beneath it. In alternative embodiments, electrode traces 784 can bepositioned in an area not beneath each active element 736, such as toavoid the need for balance traces 782 as is shown in

FIG. 2A.

In this embodiment, the second metallic layer 768 is an ultrasoundtransducer trace that includes pads 786 on which the active elements 736are mounted. The pads are electrically connected with trace lines 788.The various traces provided in the first and second metallic layers 764,768 can be configured to accomplish the connections shown in theschematic diagram of FIG. 3A.

FIG. 8 shows a portion of another embodiment of a spline of a flex-PCBcatheter, in accordance with aspects of the inventive concepts. Invarious embodiments, that is, spline 120 can take the form shown in FIG.8 .

In the embodiment of FIG. 8 , an embodiment of the flex-PCB substrate200 is shown with a plurality of ultrasound transducers 800 mountedthereon. In this embodiment, ultrasound transducer 800 includes amatching material 802 within the flex-PCB substrate 200 and an activeelement (e.g., a PZT pad) 804 on the matching material 802 and a backingmaterial 806 on the active element 804.

In FIG. 8 , the flex-PCB substrate 200 can be substantially covered by aspline support 850, which can be attached to the flex-PCB substrate 200in one or more locations. The location can be discrete, non-continuouslocations—e.g. including an unfixed portion to allow relative motionbetween, to avoid the spline 120 from becoming stiff.

The ultrasound transducer 800 can be attached to the spline support 850and/or flex-PCB substrate 200 with adhesive, crimp, and/or housing thatsurrounds (captures) ultrasound transducer 800. In this embodiment, theultrasound transducer 800 is coupled to the spline 120 using a housing810. The housing 810 can include an inner housing component 812, and thetwo can substantially surround and secure the ultrasound transducer 800.The housing 810 can be coupled or secured to the spline 120 via any or avariety of securing mechanisms. In FIG. 8 , the housing 810 is securedto spline 120 using one or more clips 814.

A benefit of the two piece protective cups, i.e., housing 810 and innerhousing component 812, is to secure the ultrasound transducers 800 tothe array and to protect the flex-PCB substrate to active element 804(e.g., PZT) bond from side loads.

FIG. 9A is a perspective view of an embodiment of a flex-PCB catheter,in accordance with aspects of the inventive concepts. In the embodimentof FIG. 9A, the expandable assembly 110 includes a plurality of splines120 configured as shown in the embodiment of FIG. 8 . In thisembodiment, the ultrasound transducers 800 are coupled to the splines120 using a housing 810. However, in other embodiments, the ultrasoundtransducers 800 could be coupled to the splines 120 in different mannersand/or different electronic elements could be included.

In this embodiment, an array of ultrasound transducers 800 and sensingelectrodes 152 are substantially equally distributed across a number ofsplines 120—shown in an expanded state. Proximal ends (nearest the shaft114) of the splines 120 are attached to a distal end of the shaft 114,such as at a location on or within shaft 114, or between shaft 114 andan inner, translatable (i.e. advanceable and retractable) shaft 910.Distal ends of the splines 120 are connected to distal end of innershaft 910, which is retracted and advanced to expand and collapse,respectively, the expandable assembly 110. Inner shaft 910 can beadvanced and retracted via a control on a proximal handle, such ascontrol 113 of handle 112 of FIG. 1 . Inner shaft 910 can include alumen 912, such as a lumen constructed and arranged to receive aguidewire.

FIG. 9B is a sectional view of a shaft portion of an embodiment offlex-PCB catheter of FIG. 9A, in accordance with aspects of theinventive concepts.

There are three different tubes in this embodiment. The outer tube or1^(st) tube is shaft 114, which surrounds the other two tubes as well asmicro coax cables 310. Shaft 114 can comprise a diameter and otherwisebe constructed and arranged to be inserted through a transseptal sheathor other introduction device, such as introducer 10 of FIG. 1 , todeliver the flex-PCB catheter 100 internal to the body. The 2^(nd) tube,shaft 920 comprises a tube with multiple radially outward facingprojections which effectively create multiple lumens 921 between shaft114 and shaft 920 (e.g. the 6 lumens shown in FIG. 9B). In someembodiments, lumens 921 comprises between 2 and 12 lumens. In someembodiments, shaft 114 and shaft 920 comprises a single structure, suchas a single extrusion of plastic material made from a die that createsthe lumens 921.

Lumens 921 house and segregate/group the wires 115 (e.g., micro coaxcables 310). Shaft 114, inner shaft 910 and/or lumens 921 provide radialsupport to flex-PCB catheter 100. Shaft 920 includes a central lumen,channel 922, for a 3^(rd) tube, an inner, translatable shaft 910. Theinner shaft 910 includes lumen 912 which can be configured to receive aguidewire for over-the-wire insertion of flex-PCB catheter 100 into orout of a body, such as into or out of a heart chamber. Alternatively oradditionally, lumen 912 can be used to pass a second electrode, toinject fluid, such as contrast media, or the like. The lumen 912 extendsfrom at least a proximal end of the shaft 114 (e.g. from the handle 112,shown in FIG. 1 ) to a distal end of shaft 114. Shaft 910 can beoperably connected to a control on a handle, such as control 113 ofhandle 112 of FIG. 1 .

In various embodiments, advantages of the flex-PCB catheter 100 include:a 360×360 isochronal map of electrical activity of the heart, rapidacquisition of cardiac chamber geometry, low profileinsertion/retraction (e.g. due to staggered connection points asdescribed hereinabove), enhanced flexibility (e.g. due to the flexiblePCB construction), reduced cost (e.g. due to the flexible PCBconstruction), and variable profile. “Over-the-wire” design facilitatessafe, efficient catheter placement to a body location, such as within aheart chamber. The flex-PCB approach enables cost-reduced, efficient andcompact electrical communication among elements of the flex-PCBcatheter.

In various embodiments, the 1^(st) tube (shaft 114) has an outerdiameter less than about 15 Fr, such as less than 11 Fr or less than 9Fr, such as to be introduced through a 15 Fr, 11 Fr or 9 Fr transseptalsheath. Inner shaft 910 can be configured to be advanced over a 0.032″to 0.038″ diameter interventional guidewire.

In various embodiments, 1 to 12 splines can be used, with 6 splinespresently preferred. When 6 splines are used, the angle between eachpair of splines can be similar, i.e. approximately 60° with 6 splines toachieve 360° coverage. With a different number of splines, a differentangle between splines could be used. In some embodiments, dissimilarangular separation between splines can be employed.

In various embodiments, a diameter of expandable assembly 110 in itsexpanded state is about 1 to 4 cm, but about 2.5 cm is presentlypreferred.

Various materials can be used for construction of various devicesdiscussed herein. For example, the splines can comprise or be made fromnickel titanium alloy, which is presently preferred, stainless steel,cobalt chromium, and some rigid plastics, such as polyimide or PEEK, asexamples.

The expandable assembly 110 can include an array of components. Forexample, the flex-PCB substrate is provided with ceramic PZT materialfor ultrasound, and gold pads for electrodes, e.g., coated withimpedance lowering coatings, such as PEDOT or IrOx.

One or more of the shafts, e.g., outer shaft 114, inner shaft 910,and/or multi-lumen shaft 920, can be comprised of a metal or plasticbraid (e.g. a stainless steel braid), with flat wire preferred,encapsulated by a thermoplastic material (e.g., Pebax, Nylon,Polyurethane) with an inner lubricious liner (e.g., PTFE, FEP, Nylon).

Referring now to FIG. 10 , a perspective view of the distal portion of asystem 2 for diagnosing and/or treating a heart arrhythmia or otherheart condition, such as atrial fibrillation and/or ventriculartachycardia, is illustrated. The system 2 includes an introducer 10, aflex-PCB catheter 100 and an ablation catheter 1000. Introducer 10 canbe configured similar to introducer 10 of FIG. 1 , including shaft 14sized to slidingly receive flex-PCB catheter 100. Flex-PCB catheter 100comprises a shaft 920, and catheter 1000 includes a shaft 1010. Shaft920 includes an inner lumen 912 configured to slidingly receive shaft1010 of catheter 1000. Shaft 920 can be of similar construction to shaft114 of FIG. 1 , with the addition of lumen 912.

The diagnostic flex-PCB catheter 100 and catheter 1000 are constructedand arranged for insertion into a body location, such as the chamber ofa heart. Shafts 920 and 1010 are typically constructed of sufficientlyflexible material to allow insertion through the tortuosity imposed bythe patient's vascular system. Attached to the distal end of shaft 920is expandable assembly 110, which can be of similar construction toexpandable assembly 110 of FIG. 1 . As shown in FIG. 10 , expandableassembly 110 has been advanced from the distal end of shaft 14 ofintroducer 10 such that expandable assembly 110 is radially expanded.Expandable assembly 110 includes a plurality of electrodes 152 and aplurality of ultrasound transducers 154 on splines 120 forming a basketarray or basket catheter, in this embodiment. In the embodiment of FIG.10 , two electrodes 152 are positioned between some pairs of ultrasoundtransducers 154. Any number, ratio and placement of electrodes 152,ultrasound transducers 154, and/or other electronic elements (e.g. othersensors or transducers) can be included. Expandable assembly 110includes a ring-shaped opening on its distal end, opening 1030 sized andpositioned to allow the distal end of catheter 1000 to exit therethrough.

Shaft 1010 of ablation catheter 1000 includes at least one ablationelement 1020, positioned at the tip or otherwise on a distal portion ofshaft 1010. Ablation element 1020 is constructed and arranged to deliverenergy to tissue, such as when ablation catheter 1000 is attached to asource of energy, such as radiofrequency energy and/or other energy typein accordance with known principles.

In various embodiments, the flex-PCB catheter 100, as a diagnosticcatheter, can be used for mapping tissue, such as an organ or portion ofan organ (e.g. a portion of a heart wall). The flex-PCB catheter 100 caninclude one or more ultrasound transducers, such as ultrasoundtransducers 154, these transducers used to provide two or threedimensional distance information such as distance information used tocreate a two or three dimensional map of tissue, determine relativeposition of tissue such as tissue walls and/or determine devicelocations such as relative locations of one or more portions of a deviceof system 2 or another device. The flex-PCB catheter 100 can include oneor more electrodes, such as one or more electrodes 152, such aselectrodes used to record physiologic electric activity such aselectrical activity of the heart, or to measure a transmitted electricalsignal such as a signal used to measure a distance between the electrodeand another electrode. Three dimensional anatomical mapping informationcollected by flex-PCB catheter 100 can be used by the electronic module360 of FIG. 3B to create a three dimensional display of an anatomicallocation of which at least a portion is to be treated by ablationcatheter 1000. For example, the flex-PCB catheter 100 can be coupled toa computer system configured to display anatomical mapping informationgenerated by the flex-PCB catheter 100, such as volumes, locations,shapes, contours, and movement of organs, nerves, and other tissuewithin the body. The flex-PCB catheter 100 can be coupled to thecomputer system to display the electrical mapping information, such asto display dipole mapping or other information, as an example.

Additionally, the location of ablation catheter 1000 or other inserteddevices can be displayed, such as their position relative to tissue orthe flex-PCB catheter 100. For example, flex-PCB catheter 100 can beused to map the heart, while ablation catheter 1000 can be directed to atissue location in the heart targeted for treatment (e.g. targeted fortreatment based on information provided by the flex-PCB catheter 100).For example, ablation catheter 1000 can be configured to ablate cardiactissue to treat a patient suffering from a cardiac arrhythmia, such asatrial fibrillation, atrial flutter, supraventricular tachycardias(SVT), Wolff-Parkinson-White syndrome, and ventricular tachycardias(VT). An ablation catheter is described herein as a form of a treatmentdevice for purposes of conveying aspects of the invention, but adifferent type of treatment device (e.g., a pacing device; adefibrillation device; a stent delivery device; a drug delivery device,a stem cell delivery device, or the like) can be used in otherembodiments in combination with flex-PCB catheter 100. In someembodiments, one or more of these treatment devices can be insertedthrough the lumen 912 of the flex-PCB catheter 100.

In some embodiments, the flex-PCB catheter 100 can be configured toaccess the left atrium of the patient while utilizing a singletransseptal puncture through which all the catheter components canaccess the left atrium (and subsequently the left ventricle in somecases). In other embodiments, the flex-PCB catheter 100 can beconfigured to access the left ventricle of the patient while utilizing asingle crossing of the aortic valve through which all the cathetercomponents access the left ventricle (and subsequently the left atriumin some cases).

In some methods, shaft 14 is inserted through the atrial septum and intothe left atrium, followed by the insertion of the flex-PCB catheter 100through a lumen of shaft 14. Subsequently, ablation catheter 1000 isinserted through the lumen 912 of shaft 920. In other methods, shaft 14is inserted into the left atrium, followed by the simultaneous insertionof the flex-PCB catheter 100 and ablation catheter 1000 (e.g. theflex-PCB catheter 100 is inserted with ablation catheter 1000 residingat least partially within lumen 912). In some embodiments, shaft 14 caninclude or be a steerable sheath. In some embodiments, the flex-PCBcatheter 100 and/or ablation catheter 1000 are steerable, so thatmanual, semi-automatic, or automatic steering can be performed by anoperator and/or a robotic control assembly.

The flex-PCB catheter 100 can be positioned in the left atrium and canprovide information selected from the group comprising: electricalinformation, such as surface charge information, anatomical geometryinformation, such as heart wall surface information or heart wallthickness information, other physiologic and anatomical information,such as those known in the art, and combinations of these. Shaft 920 ofthe flex-PCB catheter 100 can be configured to be inserted into theheart via the venous system, for example a vein in a leg or a vein in aneck. Shaft 920 can include a braid within its outer and inner surfaces,not shown, but typically a braid of plastic or metal fibers that enhancethe structural integrity and performance of shaft 920. In someembodiments, the braid of shaft 920 can include conductors, such aswires 115 of FIG. 1 .

In various embodiments, the inserted catheter or other elongated deviceinserted through lumen 912 can include another catheter, such as adiagnostic catheter configured to record signals from a locationselected from a group comprising: the left atrium, the right atrium, theBundle of HIS, the right ventricular apex, a pulmonary vein, and thecoronary sinus. Alternatively or additionally, the inserted catheter cancomprise another type of catheter device.

In various embodiments, the expandable assembly 110 is constructed andarranged to be biased in the expanded shape shown in FIGS. 9A and 10 ,as examples. The expanded geometry of expandable assembly 110, includingat least two or more splines 120 in an expanded or partially expandedstate, can be described as a “basket” having a substantially hollowcenter and spaces between adjacent splines 120. In the illustratedembodiment, the basket is spherical, but can include any suitable shape,for example an ellipsoid. Thus, in other embodiments, expandableassembly 110 can comprise different shapes or combination of shapes,such as an array of splines 120 where two or more splines 120 comprisesimilar or dissimilar shapes, dimensions or configurations. In someembodiments, two or more splines 120 can include a varied radius ofcurvature.

As discussed above, the expandable assembly 110 can be biased in anexpanded or collapsed (non-expanded or contracted state). In an example,expandable assembly 110 can be self-expanding such that splines 120 areresiliently biased in the curved geometry shown in FIGS. 9A and 10 .Expandable assembly 110 can automatically expand when it exits thedistal end of shaft 14, such as by retraction and/or advancement,respectively, of a shaft, such as shaft 920 of FIG. 9A.

Each spline 120 can include a similar or dissimilar arrangement ofelectrodes 152 and/or ultrasound transducers 154 as an adjacent spline120 or any other spline 120 in expandable assembly 110. In someembodiments, expandable assembly 110 includes eight splines 120, whereeach spline 120 can include two to eight electrodes 152 and two to eightultrasound transducers 154. In some embodiments, expandable assembly 110includes six splines 120, where each spline 120 can include eightelectrodes 152 and eight ultrasound transducers 154. In someembodiments, one or more splines 120 include a number of electrodes 152that is greater or less than the number of ultrasound transducers 154that are included on that spline 120. For example, a spline 120 caninclude seven electrodes 152 and either six or eight ultrasoundtransducers 154. In some embodiments, a set of electrodes 152 andultrasound transducers 154 can be arranged in an alternatingarrangement, such that one or more single ultrasound transducers 154lies between two electrodes 152. In some embodiments, some sets ofelectrodes 152 and ultrasound transducers 154 can be arranged such thatone or more single electrodes 152 is positioned between two ultrasoundtransducers 154.

In various embodiments, electrodes 152 can be configured to recordelectric signals, such as voltage and/or current signals. The recordedsignals can be used to produce electrogram information, dipole mappinginformation, distance information, such as the distance between anydevice and/or component of system 2, and other information orcombinations of information described in detail herein. Any or allelectrodes 152 can comprise a dipole mapping electrode, such as anelectrode with an impedance or other electrical property configured toprovide information related to surface charge or other dipole mappingparameter.

In some embodiments, the electrodes 152 are of sufficiently lowimpedance, e.g., in the range less than 10,000 ohms, such as to achievehigh-fidelity recording of signal frequencies greater than or equal to0.1 Hz. In some embodiments, one or more electrodes 152 include aniridium oxide coating, such as to reduce the impedance of electrodes152. Alternatively or additionally, numerous forms of coatings or othertreatments can be included with one or more electrodes 152, such as aplatinum black coating or a carbon nanotube layer. In addition or as analternative to recording electric signals, electrodes 152 can beconstructed and arranged to deliver electric energy, such asradiofrequency energy. In some embodiments, flex-PCB catheter 100 candeliver therapy, such as an ablation therapy delivered to tissue, inaddition to its function as a diagnostic catheter, e.g. providingelectrical, anatomical and/or device mapping information. In someembodiments, one or more electrodes 152 each comprise one or more coils,such as when the one or more coils are configured to create one or moremagnetic fields.

In various embodiments, electrodes 152 can include various materials,such as non-polarizing metals and/or polarizing metals. In someembodiments, one or more electrodes 152 comprise at least one non-noblemetal such that electrodes 152 oxidize when in contact with at least oneof blood, blood plasma or saline solutions. In some embodiments,electrodes 152 include a coating, for example a coating selected from agroup comprising: a metal oxide coating, a conductive polymer coating,and combinations of these. In some embodiments, one or more electrodes152 can include an outer layer and an inner layer, such as when theouter layer comprises an impedance lowering coating or other layer andthe inner layer comprises a layer configured to bond the outer layer tothe metallic and/or other remaining portion of the one or moreelectrodes 152.

In some embodiments, the ultrasound transducers 154 can be configured torecord distance information, such as the distance between any deviceand/or component of the flex-PCB catheter 100 and tissue, such ascardiac wall or other solid tissue. Ultrasound transducers 154 caninclude a construction comprising: single or multi-element piezoelectricceramics, piezoelectric micro-machined ultrasound transducers (pMUT),capacitive micro-machined ultrasound transducers (cMUT); piezoelectricpolymers, and combinations of these, as examples.

The ablation element 1020 of the ablation catheter 1000 can include afunctional element selected from a group comprising: one or moreelectrodes, a vessel configured to deliver cryogenic energy, a laserdiode, an optical fiber configured to deliver ablative energy, amicrowave energy delivery element, an ultrasound energy deliveryelement, a drug, stem cell, or other agent delivery element, amechanical or other ablation device delivery element, and combinationsof these. In the case where ablation element 1020 includes one or moreelectrodes, the electrodes can include electrodes constructed andarranged to deliver radiofrequency (RF) energy. In the case of multipleelectrodes, the electrodes can be configured for bipolar RF energydelivery. Ablation catheter 1000 can be operably connected to anexternal device configured to deliver energy to ablation element 1020,such electronic module 360 of FIG. 3B. Typical energy delivered byablation element 1020 comprises an energy selected from a groupcomprising: electromagnetic energy, such as radiofrequency energy,cryogenic energy, laser energy, light energy, microwave energy,ultrasound energy, chemical energy, and combinations of these.

Similar to the introducer 10 and shaft 14, flex-PCB catheter 100 and/orablation catheter 1000 can be steerable, such as via a pull wire andanchor, as is known in the art. Ablation catheter 1000 can be steeredand advanced by an operator, such as a clinician, so as to exit at anyopening of the expandable assembly 110, including the space between twosplines 120 or through opening 1030, such as to be further advanced tocontact and ablate cardiac tissue.

While the foregoing has described what are considered to be the bestmode and/or other preferred embodiments, it is understood that variousmodifications can be made therein and that the invention or inventionscan be implemented in various forms and embodiments, and that they canbe applied in numerous applications, only some of which have beendescribed herein. It is intended by the following claims to claim thatwhich is literally described and all equivalents thereto, including allmodifications and variations that fall within the scope of each claim.

1. (canceled)
 2. A device that is configured to be inserted into a bodylumen, comprising: an elongate shaft comprising a proximal end and adistal portion; an expandable assembly positioned on the distal portionof the elongate shaft and configured to transition from a radiallycompact state to a radially expanded state, wherein the expandableassembly comprises a plurality of splines; a plurality of electrodes anda plurality of ultrasound transducers positioned on the plurality ofsplines and configured to at least on of receive or transmit electricalsignals, wherein each of the plurality of ultrasound transducerscomprise a first terminal and a second terminal; and a plurality ofcommunication paths selectively coupling the plurality of electrodes andthe plurality of ultrasound transducers to an electronic moduleconfigured to process the electrical signals, wherein the plurality ofcommunications paths comprises a first set of conductors and a secondset of conductors, wherein the electrodes of the first set of electrodesand the first terminals of the plurality of ultrasound transducers arecoupled to the conductors of the first set of conductors, and the secondterminals of the plurality of ultrasound transducers are coupled to theconductors of the second set of conductors.
 3. The device according toclaim 2, wherein each conductor of the first set of conductors iscoupled to an electrode of the plurality of electrodes, and the firstterminal of an ultrasound transducer of the plurality of ultrasoundtransducers.
 4. The device according to claim 2, where each conductor ofthe second set of conductors is coupled to the second terminal of two ormore of the plurality of ultrasound transducers.
 5. The device accordingto claim 4, wherein each of the two or more ultrasound transducers areindividually addressable by the electronic module.
 6. The deviceaccording to claim 2, further comprising a flexible printed circuitboard substrate, wherein the flexible printed circuit board substrate iscoupled to the splines of the expandable assembly, wherein the pluralityof electrodes and the plurality of ultrasound transducers are coupled tothe flexible printed circuit board substrate, and at least a portion ofthe plurality of communication paths are positioned at least one of onor within the flexible printed circuit board substrate.
 7. The deviceaccording to claim 6, wherein each of the plurality of ultrasoundtransducers comprises as matching layer.
 8. The device according toclaim 7, wherein the matching layer comprises at least a portion of theflexible printed circuit board substrate.
 9. The device according toclaim 6, wherein the flexible printed circuit board substrate comprisesmaterials selected from a group comprising: polyimide; polyester; nylon;Pebax; liquid crystal polymer; and combinations thereof.
 10. The deviceaccording to claim 2, wherein the device comprises a dipole mappingdevice.
 11. The device according to claim 2, wherein the plurality ofelectrodes comprises at least 8 electrodes, and the plurality ofultrasound transducers comprises at least 8 transducers.
 12. The deviceaccording to claim 2, wherein the plurality of splines comprises atleast two splines with at least two ultrasound transducers positioned oneach of the at least two splines.
 13. The device according to claim 12,wherein the at least two ultrasound transducers mounted to a firstspline are linearly staggered from the at last two ultrasoundtransducers mounted to a second spline, such that a protrusion of anultrasound transducer on the first spline extends between protrusions ofthe at least two ultrasound transducers on the second spline.
 14. Thedevice according to claim 2, further comprising one or more coaxialcables each comprising an inner conductor and a shield, wherein at leastone of the first set of conductors comprises the inner conductor of oneof the one or more coaxial cables, and at least on of the second set ofconductors comprises the shield of one of the one or more coaxialcables.
 15. The device according to claim 14, wherein the one or morecoaxial cables comprise at least two coaxial cables, and wherein theshields of the two or more coaxial cables are electrically connected.